HDMI is a specification that integrates audio and video information into a single digital interface to be used with, for example, digital video disc (DVD) players, digital television (DTV), high definition TV (HDTV), set-top boxes, and other audio and/or video devices. A key element of HDMI is the ability to utilize high bandwidth digital content protection (HDCP). Notwithstanding, the high definition multimedia interface also utilizes core technologies provided by the digital visual interface (DVI). High bandwidth digital content protection provides a method for protecting copyrighted digital content that utilizes the digital visual interface by encrypting data transmitted between a source and a destination device. The source device may include, but is not limited to, a computer, a set-top box, D-VHS, or a DVD player. The receiver destination device may be a television, projector, a LCD display, or a plasma panel, for example.
The digital visual interface is a standardized protocol, which facilitates the coupling of analog and digital monitors using a single connector. The digital visual interface is a 24-bit RGB interface, which utilizes transition minimized differential signaling (TMDS), the latter of which has become quite popular. A DVI link utilizes three (3) pairs of differential digital signals, each pair carrying low voltage signals representative of the red (R), green (G) and blue (B) signal components. Each of the pairs may also carry synchronization information. Additionally, a fourth pair of wires carries a pixel clock signal. A serial 8-bit RGB signal carries information at a speed of up to 1.65 Gbps with an aggregate link speed of 4.95 Gbps, but an effective transfer rate of 3.96 Gbps. In order to minimize transitions at such high data rates, a 10-bit encoding scheme is utilized.
A DVI connector permits two links to be coupled to the connector. To minimize connector size, the two links share the same clock signal, resulting in a maximum data rate of 9.9 Gbps. DVI also includes a display data channel (DDC), which permits a video source such as a PC to communicate with a DVI capable display. The DDC utilizes a low speed, bi-directional two-wire bus similar to an I2C bus. A digital signal that is transmitted to an analog monitor may be converted into an analog signal using a DVI connector. In instances where a digital monitor is utilized, then no conversion is performed. However, in the case of an analog monitor, then D/A conversion is required. The popularity of DVI along with various standardized changes has resulted in a plethora of products now supporting DVI.
The high definition multimedia interface supports standardized, enhanced, or high-definition video formats along with multi-channel surround sound audio. Some of the benefits of high definition multimedia interface may include, but are not limited to, uncompressed digital video, a bandwidth of up to five gigabytes per second and a single connector instead of multiple connectors and cables. The high definition multimedia interface may also be adapted to facilitate communication between a video source and, for example, a DTV.
Transition minimized differential signaling is a signaling technique that produces a transition controlled, DC balanced series of characters from an input series of data bytes. In a long string of logic zeros and logic ones, bits are selectively manipulated in order to keep the DC voltage level of the overall signal centered around a particular signal threshold. Transition minimized differential signaling may use, for example, bit inversion to maintain a particular DC biased signal. A signal threshold may determine whether a received data bit is at a voltage level equivalent to logic zero (0) or at a level equivalent to logic one (1).
Various silicon-based versions of transition minimized differential signaling encoders and receivers have been developed. One version of the high definition multimedia interface implements a new coding scheme which is referred to as TERC4. The TERC4 encoding scheme maps sixteen (16) 4-bit characters to 10-bit symbols. The new encoding scheme also includes various symbols, which may be utilized as guard bands. The high definition multimedia interface specification provides an adequate description of how the guard bands may be utilized. One released revision of the bandwidth digital content protection encryption standard include various algorithms which may be utilized for encrypting of HDMI data. TERC4 symbols and guard band symbols, which may be collectively known as HDMI symbols, are 10-bits in length and have five (5) logic ones (1s) and five (5) logic zeros (0s), to ensure that they are DC balanced. In this regard, the high definition multimedia interface (HDMI) symbols are valid TMDS codewords and the HDMI codewords are mapped to a unique un-encoded TMDS byte. A one-to-one mapping may be used to map the high definition multimedia interface codewords into the unique un-encoded TMDS byte.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.